Many industrial processes benefit from the use of biocides to reduce corrosion or otherwise aid the process. Microorganisms are one common cause of corrosion. Sulfate-reducing bacteria (“SRB”), for example, oxidize organic compounds found in many drilling fluids and reduce sulfates to sulfides, in particular, hydrogen sulfide (H2S) and hydrosulfide ions (HS−). Boreholes, or deep subterranean holes drilled into the earth, often expose anaerobic conditions which promulgate SRB and other potentially harmful microorganisms.
Since bacteria are the ultimate cause of one major source of corrosion, biocides are often included with conventional drilling fluid and in source water. These biocides are intended to kill or reduce the bacteria, H2S, organic carbons, and metals that often prevent successful outcomes in geotechnical engineering boreholes. Examples of biocides used in drilling fluid include chlorine, glutaraldehyde, sodium hydroxide, and sodium hypochlorite. However, conventional biocides used in drilling and other industrial processes have significant drawbacks. Typical biocides are dangerously toxic and/or are relatively expensive to use in adequate volumes. Many biocides break down or dissipate quickly and, therefore, must regularly be replaced, which leads to increasing costs. Also, some biocides require relatively high concentrations to be effective, which can have detrimental effects on the surrounding ecosystem or to well workers or other personnel. One drawback that has drawn particular concern in recent years is toxicity of biocides. Toxic biocides may be leaching from well bores into aquifers or other unintended locations. The potential environmental drawbacks of using these biocides in drilling fluids may result in further regulation and increased cost in the future. Disposing of drilling fluids that contain these toxic biocides results in significant costs and concerns. Additionally, the high concentrations of conventional treatment materials may contribute to the corrosion of casings, pumps, pipelines and other engineered materials. Also, recovered drilling fluids or produced water may contain elevated concentrations of various toxic chemicals, metals, and hydrogen sulfide, and other gases.